Production forecasting involves attaching a timescale to production recovery and it is one of the most vital roles of reservoir engineering. It underpins the cashflow of any project and can make the difference between a project being sanctioned or abandoned. The complexity of the role is underscored by the requirement to integrate multiple and diverse disciplines including subsurface characterisation, surface network configuration, production philosophy, economic limits, business decisions and operational constraints.
Unlike production forecasting for oil fields, gas forecasting is further complicated by long-term contracts and the need to meet contractual obligations. This requirement means that gas companies need to correctly predict the execution of future projects to ensure that they have enough gas security to satisfy their contractual obligations. Usually, in gas forecasting, multiple fields with diverse fluid properties are produced simultaneously and this further introduces the complication of gas quality and maximizing the value of by-products like condensate and natural gas liquids. These complexities imply that an integrated gas forecasting model is required to accurately predict production for a gas field. There are many such products available including company proprietary software for internal use only and commercial software in the public domain. One such commercial product is the Integrated Production Model (IPM) suite of software by Petroleum Experts (PETEX).
The following industry standard acronyms are used in this paper:    BBL=Barrel    BHP=Bottom Hole Pressure    dP=Pressure Drop    Fw=Water fractional flow    GAP=General Allocation Package—IPM Software    GOR=Gas Oil Ratio    IAM=Integrated Asset Management    IPM=Integrated Production Model    IPR=Inflow Performance Relationship    LNG=Liquefied natural gas    LPG=Liquefied Petroleum Gas    MBAL=Material Balance—IPM Software    MCP=Major Capital Project    MMSCF=Million Standard Cubic Feet    NOJV=Non-Operated Joint Venture    NPV=Net Present Value    PETEX=Petroleum Experts    PV=Pore Volume    PVT=Pressure Volume Temperature    QC=Quality Control    SCAL=Special Core Analysis    Tmax=Technical Max    VBA=Visual Basic for Applications    VLP=Vertical Lift Performance    WGR=Water Gas Ratio